The invention relates to an ablating arrangement for the targeted production of local lesions in living tissue inside a body, particularly in a heart, comprising: at least one energy source; a holding element; a plurality of energy uncoupling elements mounted on the holding element; a plurality of energy transmission lines connecting the at least one energy source to the energy transmission lines for one of activating and interrupting a connection between the at least one energy source and respectively one energy uncoupling element.
Such ablating arrangements are known and have proven themselves in clinical applications. The energy source (e.g. a HF generator and amplifier) can be connected to different electrodes of a multi-polar catheter through manually operated switches, so as to achieve a lesion pattern desired by the doctor.
These manually operated arrangements are very flexible with respect to use, but are difficult to operate.
Another type of ablation arrangement is known from the international patent application WO-A-97/20510. The HF ablation system, described therein, can be used to release HF energy simultaneously and with predetermined phase coordination via several electrodes of a multi-polar catheter. The number of power modules used for this corresponds to the number of electrodes.
The last-named arrangement is structurally very involved and expensive. Also, the various electrode systems are not mutually uncoupled, so that measuring circuits and control circuits, based thereon, influence each other. It is therefore the object of the invention to specify a cost-effective and easy to operate ablation arrangement.
This object is solved with an ablation arrangement of the type first mentioned above and further comprising program control means, including a program memory storing a control program, for performing a time-sequential actuation of at least some of the switching elements according to the control program.
The invention includes the idea of automating the ablation to such a degree that a mode for connecting the energy source to the individual uncoupling elements for introducing energy at predetermined locations to the tissue can be determined ahead of time and individually, and can subsequently be realized quickly and in a timely fashion with an automatic sequence. The physician is thus relieved of having to activate switches continuously during an operation while not being restricted in his/her freedom to position the lesion regions according to the concrete findings. On the contrary, the physician can focus more attention on the patient or the positioning of the catheter. By shortening the ablation procedure, the risks of radiation stress and an incorrect positioning of the catheter are reduced.
For this purpose, one advantageous modification of the invention provides an ablation program memory, having a number of storage regions that correspond to the number of energy output elements, as well as means for influencing an ablation program stored in the ablation program memory in dependence on at least one variable, which is input prior to or during the treatment and/or is measured during the treatment. Thus, while the basic mode of sequentially connecting the individual uncoupling locations with the energy source is determined ahead of time, there are degrees of freedomxe2x80x94in addition to the also existing options for an emergency shut-downxe2x80x94above all with respect to the concrete or pre-programmed time-dependent sequence and particularly for taking into account actually obtained measuring values, which reflect the status of the treatment.
One of the preferred embodiments of the HF ablation arrangement provides that the energy source is designed as an HF voltage source (with corresponding amplifier), the holding element as a catheter body, the energy uncoupling elements are designed as electrodes, the energy transmission lines as electrical lines (these parts together form a multipolar ablation catheter, known per se), and the switching elements as electromechanical or electronic switches.
The energy source as well as various ablation catheters for use with the invention are known per se and do not need to be described in further detail here. Relays or semiconductor switches, for example, can be used as switching elements (these are preferred in CMOS technology). The invention makes it possible to essentially simplify the device technologically and reduce costs by using only a single energy-source for the multiplex operation, specifically a single HF amplifier. Owing to the option of a synchronous switching of the HF line and temperature measuring points, several temperature control circuits can be operated, which do not interfere with each other.
In principle, the invention can also be used with different types of ablation arrangements, for example if the energy source is designed as an high-power radiation source, particularly a laser source, the holding element as a catheter body, the energy transmission lines and the energy uncoupling elements are designed as a waveguide arrangement and the switching elements are designed as electro-optical switching elements.
In favorable embodiments, the energy uncoupling elements simultaneously serve as sensors. A measuring signal processing unit for evaluating the recorded measuring signals is provided, which can be additionally connected to the energy transmission lines. The individual energy uncoupling elements in this case are switched by the program control means to the input of the first measuring signal processing unit by way of the switching elements.
In a preferred HF ablation arrangement, the electrodes are designed to pick up in particular intracardiac electrogram signals, including monophase action potentials (MAP). The first measuring signal processing unit is designed for evaluating these signals. An arrangement for the lesion of heart tissue to treat tachyarrythmias is additionally provided with a stimulation pulse generator, which can be linked via the switching elements to the energy transmission lines and thus to the electrodes by using the program control means. With such a laser ablation device, it is possible in principle to use at the same time for observing the tissue or for the optical detection of measured values by means of fiber optics for coupling the laser energy into the tissue.
In these embodiments, the program control is used to simplify not only the therapy sequence, but also the associated detection of measured values and, if necessary, any preceding stimulation, which makes it even easier for the physician to operate this device.
The above-mentioned means for influencing the ablation program comprise in particular a plurality of additional sensors (respectively associated with the energy uncoupling elements), in particular temperature sensors, a measuring signal processing unit adapted to these sensors and a memory access control connected to the processing unit output for varying the rate and/or sequence of access to the memory regions of the ablation program memory in dependence on the measuring signals and the evaluation result.
In order to further simplify the arrangement, a multiplexer is assigned to the sensors, which is controlled by the program control means in dependence of the ablation program and is designed for transmitting sensor signals via a lower number of sensor transmission lines, as compared to the number of sensors. The safety requirements posed to a program-controlled arrangement of the above sketched type are met in that the program control means have at least one switch-off timer, preferably two, for a safety shutdown of all energy transmission lines if one or several predetermined shutdown criteria are met.
Owing to the fact that the program control means and the switching elements for one advantageous embodiment of the invention are housed in a separate switching device, which is connected on the input side with a traditional ablation device via two serial data lines, a current supply line and a first section of the energy transmission line, a modern arrangement with high use value can be configured from existing ablation devices and catheters by adding components, designed according to the invention, for a retrofitting with little additional expenditure. A step-by-step expansion of new devices is also possible in this way. However, the integrated design in one device is preferred on the whole.